Abstract: This invention includes a speech training system that allows a student to enter any utterance to be learned and have the articulatory model movements required to produce the utterance displayed on a CRT screen. The system accepts a typed utterance, breaking it down into a set of phonemes. The set of phonemes is sent to a synthesizer, which produces a set of parameters indicating the acoustic characteristics of the utterance. The acoustic parameters are converted into articulatory parameters emphasizing the frequency, nasality, and tongue-palate contact required to produce the typed utterance. The articulatory parameters are displayed on the CRT screen. The acoustic parameters are also sent to a formant synthesizer which converts the parameters into speech output. The system measures a student's production and then evaluates the student's production against the parameters of the typed utterance for its similarity. Feedback on the similarity is displayed on the CRT screen.

Abstract: A video signal conversion system converts input video signals in a studio format, such as CCIR 601 (625/25), into output video signals in another format, such as the Phase Alternate Line (PAL) format. The horizontal line scanning frequency of the input and output signals is the same. The signal conversion system uses an output clock signal to determine the relative timing of the input and output video signals. This signal is generated by a phase-locked loop which employs a crystal-controlled VCO. The phase of the signal produced by the VCO is adjusted to maintain the sampling clock signals of the input and output video signals in a predetermined phase relationship. The phase error signal which is used to control the VCO is generated by comparing a first phase reference signal, generated from the output signal, to a second phase reference signal generated from the input signal.

Abstract: A sample rate conversion system converts from an input sample rate stream having a predetermined input sample rate to an output sample stream having a predetermined output sample rate by interpolating output samples from the input samples using first and second approximate sample rate ratios. The system includes circuitry which selects a sequence of interpolation filters from among a set of filters, the sequences being defined by one of these approximate ratios, and circuitry which monitors the magnitude of the accumulated error introduced by the approximation. When this accumulated error becomes greater than a threshold, the system changes to use a further sequence of interpolation filters based on the other approximate ratio. The accumulated error changes in a positive sense with each successive sample while one of the two approximate ratios is used. The accumulated error changes in a negative sense with each successive sample while the other of the two approximate ratios is used.

Abstract: A method for analyzing a speech signal to isolate speech and nonspeech portions of the speech signal is provided. The method is applied to an input speech signal to determine boundary values locating isolated words or groups of words within the speech signal. First, a comparison signal is generated which is biased to emphasize components of the signal having preselected frequencies. Next, the system compares the comparison signal with a threshold level to determine estimated boundary values demonstrating the beginning and ending points of the words. Once the estimated boundary values are calculated, the system adjusts the boundary values to achieve final boundary values. The specific amount of adjustment varies, depending upon the amount of noise present in the signal. The final pair of boundary values provide a reliable indication of the location and duration of the isolated word or group of words within the speech signal.

Abstract: A color video camera includes circuitry which generates a peaking signal that is applied to each of the color signals to enhance high-frequency components of the video signal relative to low-frequency components. The circuitry adds high-frequency components from the green video signal, as the peaking signal, at instants when the amplitudes of the green and red color signals are approximately equal. If there is a significant difference between the amplitudes of the red and green video signals, however, a combination of the high frequency components of both of these signals is used as the peaking signal. In one exemplary embodiment of the invention, the peaking signal includes in-band horizontal and vertical contour signals and out-of-band aperture correction signal.

Abstract: A method of manufacturing a multiple microelectrode assembly is disclosed. Micromachining technology (such as micro-electrical-discharge machining technology, laser-beam micromachining, electron-beam micromachining) is used to manufacture an electrode/base assembly. The electrode/base assembly is placed within a container; a liquid material is placed into the container; the liquid material surrounds the electrodes of the electrode/base assembly and is allowed to solidify; and the solidified liquid material in combination with the electrode/base assembly is separated from the container. The bottom (or base) portion of the electrode/base assembly is then removed. The electrodes of the electrode/base assembly comprise a plurality of rod-like members of very small (on the order of 1 micron) metallic members of preselected dimension, shape and spacing, by which they are adapted in combination with the surrounding insulating material as a multiple microelectrode assembly.

Abstract: A color video signal processing system determines when one component color signal has been limited by clipping and limits the other component color signals to maintain accurate hue in the reproduced image. In one system, the other color signals are held at their values at the instant the one signal was detected as being clipped until the signal is no longer clipped. In another system, an attenuation function is applied to the unclipped color signals when any one color signal is detected as being clipped.

Abstract: A video signal processing system uses a sequence of interpolation filters to resample a 125M video signal to produce a 244M signal. In addition, the system allows an operator to specify a desired subcarrier-to-horizontal sync (SCH) phase and a desired horizontal position. The system automatically adjusts the starting point in the sequence of filters used for the resampling operation to implement each of the requested phase shifts.

Abstract: A system for converting a digital component video signal having timing information contained therein to a digital composite video signal is described. The system has a decoder for extracting the timing information from the digital component signal, a digital memory means for storing portions of the desired digital composite signal, a memory control means for extracting the portions of said desired signal from the digital memory means in response to the timing information and a multiplexing means for combining the portions of the signal extracted from the digital memory in response to timing information of the digital component signal.

Abstract: A method of manufacturing a precision micro-filter and a micro-filter manufactured thereby is disclosed. A micro-mold is manufactured using micro-machining technology (such as micro-electrical-discharge machining technology, laser-beam micro-machining, electron beam micro-machining) to make a filter mold with a plurality of rod-like protrusions, of the shape, dimensions, and spacing required for the pores of a finished micro-filter. A molding material is placed into the micro-mold, the molding composition is allowed to solidify to form a micro-filter, the passageways of which conform precisely to the rod-like protrusions of the mold. This micro-filter is then separated from the micro-mold.

Abstract: A method and apparatus for reducing the maximum gain applied to a video signal during gamma correction are disclosed. A gamma exponent value, a black level, white level, and a desired maximum gain value are selected. A count of possible input signal values is determined. A modified black level is set equal to the desired black level. A gain limit value for the gamma correcting transfer function is calculated, and the smallest input signal for which the applied gain is less than or equal to the gain limit is determined. A black level correction factor is calculated. The modified black level is increased by the black level correction factor, and a determination is made whether the black level correction factor has decreased to less than a predetermined threshold value. The gamma correction function is recalculated and further black level corrections are added until the correction threshold is reached.

Abstract: A method and apparatus for non-linear quantization of a signal that utilizes two or more lowresolution analog to digital converters (ADCs) to allow selective increased quantization levels at desired portions of a signal. This is accomplished by using a primary ADC which provides digital output signals over a first predetermined range, and at least one secondary ADC which provides digital output signals over a smaller predetermined range for the same input values. Accordingly, any secondary ADCs have a smaller quantization step size than the first, and are utilized when finer resolution is desired. The ADCs are kept in alignment by periodically comparing the digital values produced by the ADCs for a known input analog value.